South Rockies

Fair - Forecast snowfall amounts are uncertain on Friday

Overnight and Friday: Clear periods overnight with gusty Westerly winds. Freezing level dropping to valley bottoms. Cloudy with flurries or light snow during the day. Alpine temperatures around -15.Saturday: Cloudy with light flurries and light Northwest winds. Alpine temperatures around -20.Sunday: Continued cloud with light Easterly winds and light snow. Alpine temperatures around -22.

We continue to get reports of accidentally triggered and remote triggered avalanches. There was a size 4.0 natural slab avalanche in the neighbouring Lizard range that ran full path and piled up debris including mature timber in the valley bottom. See the bottom left of the bulletin page for a list of reported avalanches for this region. I suspect that the storm slab is settling and becoming more cohesive. Forecast new snow and wind loading are expected to add a new load to this recent storm slab that may increase the sensitivity to human triggers and may result in natural avalanches.

The recent storm snow slab is now close to a metre thick and continues to settle into a cohesive slab that has become more stiff as it settles (one finger resistance). The layer of weak facetted (four finger resistance) snow that is below the storm slab has been reported as widespread on all aspects and at all elevations across the region. This is the classic firm slab over soft and weak layer that can allow for wide propagations and remote triggering. This problem may persist for days after the storm or even weeks. Forecast new snow and continued strong winds are expected to overload the weakness and cause another natural avalanche cycle. Regardless, it will continue to load above the weak layer priming conditions for large slab avalanches. The mid snowpack is strong and supportive. A deep persistent layer of facets and depth hoar near the base of the snowpack has remained dormant to this point, but may become a concern with additional load and stress on the snowpack.